In prior application Ser. No. 08/359,697, filed Dec. 20, 1994, there is disclosed a method and apparatus including flexographic printing units which enable substantially simultaneous printing of a web of paper to produce discrete documents with selective non-variable and variable information in a quick, accurate and efficient manner. For example, the prior application discloses a method of producing discrete documents with varying numbers of pages which consist of both non-variable and variable printed information during a single pass in a continuous printing operation. An example of the type of product is a telephone bill which contains multiple pages of both variable and non-variable information. The advantages of such a system are set forth in the prior application, the disclosure of which is incorporated herein by reference.
In a typical flexographic printing unit, there is provided an anilox or inker roll in contact with a supply of ink. A plate or image cylinder is in contact with the inker roll whereby ink from the supply source is transferred to the inker roll and then onto a plate cylinder. The plate cylinder, in turn, is in periodic contact with a substrate, i.e., a web of paper, formed about an impression cylinder. With the rotation of the various cylinders and inker roll, the plate cylinder is inked and its image is transferred onto the substrate. As set forth in that prior application, the flexographic print units are independently controlled by a computer to operatively engage and disengage the paper web and thereby print non-variable information using at least one of the flexographic units on each discrete document portion of the paper web.